Elevator with rollers having selectively variable hardness

ABSTRACT

An elevator system includes a roller ( 16 ) having a hardness that varies responsive to a magnetic field ( 20 ). The roller ( 16 ) rolls along a guide rail ( 28 ) to maintain a desired orientation of the elevator car ( 12 ). In one example, the roller ( 16 ) includes a membrane ( 30 ) defining a generally annular chamber ( 36 ) containing fluid ( 22 ) that changes viscosity responsive to changes in the magnetic field ( 20 ). The rollers ( 16 ) are associated with at least one magnetic field generator ( 18 ) that generates a magnetic field ( 20 ) of a selected strength. Varying the magnetic field varies the hardness of each roller ( 16 ) to control vibrations of the elevator car ( 12 ) to improve ride quality.

FIELD OF THE INVENTION

This invention generally relates to a roller guide assembly for anelevator system. More specifically this invention relates to a rollerguide having a roller hardness that is selectively variable.

DESCRIPTION OF THE PRIOR ART

Elevator systems typically include a car that moves within a hoistway totransport passengers or items between various levels in a building.Guide rails mounted within the hoistway guide the elevator car withinthe hoistway. The elevator car includes a plurality of roller guidesthat guide the car along each guide rail. Inconsistencies in the guiderails can cause unwanted vibrations of the elevator car. In someinstances, undesirable vibration requires guide rail realignment.Further, guide rails are fabricated within a specific set of tolerancesto provide a desired elevator ride quality. Restrictive tolerances forguide rails require costly fabrication techniques and processes that addto the cost of the elevator system.

Typically, roller guides are mounted to the elevator car with spring ordamper assemblies to cushion and absorb some of the inconsistenciespresent along the guide rail and vibrations transmitted to the elevatorcar. Such roller guide assemblies can only accommodate a fixed amount ofguide rail inconsistency and associated elevator car vibrations. Thefixed dampening rate provides optimal ride quality within a limitedoperational range. Further, the capabilities of springs and dampers todampen out vibration are constrained by alignment requirementsnecessitated by increased elevator car speeds. Ride quality for theelevator car is balanced between the desire for a smooth ride andfunctional elevator parameters such as lift weights and elevator carspeeds.

Accordingly, it is desirable to develop a roller guide assembly capableof adapting to vibrations and guide rail inconsistencies to improveelevator ride quality.

SUMMARY OF INVENTION

In embodiment of this invention is a roller guide assembly including aroller having a hardness variable in response to a magnetic field.

In one example, the inventive roller includes a membrane defining agenerally annular chamber containing a fluid that changes viscositycharacteristics in the presence of an applied magnetic field. A magneticfield generator associated with each roller generates a magnetic fieldof varying strength to changes viscous properties of the fluid. Thevariable viscous properties of the fluid result in corresponding changesin roller hardness. A change in roller hardness optimizes dampeningcharacteristics according to currently sensed elevator orientation andoperational conditions (i.e., vibrations) to provide improved ridequality.

Accordingly, this invention improves elevator car ride quality byvarying roller hardness according to current elevator operatingconditions.

BRIEF DESCRIPTION OF THE DRAWINGS

The various features and advantages of this invention will becomeapparent to those skilled in the art from the following detaileddescription of the currently preferred embodiment. The drawings thataccompany the detailed description can be briefly described as follows:

FIG. 1 is a schematic view of an elevator car including example rollerguide assemblies designed according to this invention;

FIG. 2 is a schematic view of an embodiment of a magnetic fieldgenerator;

FIG. 3 is a schematic view of another embodiment of a magnetic fieldgenerator;

FIG. 4 is a schematic view of a roller guide assembly contacting a guiderail; and

FIGS. 5 and 6 are illustrations of a roller guide designed according tothis invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, a roller guide assembly 14 for an elevator system10 includes a roller 16 having a hardness variable in response toexposure to a magnetic field 20. The roller guide assemblies 14 aresupported for movement with a car 12. The rollers 16 are in rollingcontact with surfaces of a guide rail 28.

The hardness of each roller 16 varies in response to changes in themagnetic field 20 to counteract vibrations, for example. Vibrations canbe caused by inconsistencies in the guide rail 28 or by combinations ofspeeds and loads transported by the elevator car. Further, liftingmotors and other elevator system components can contribute toundesirable vibrations of elevator car 12. Variation in the hardness ofeach of the rollers 16 adapts to vibrations of varying magnitude toimprove ride quality.

A controller 24 is programmed to selectively vary the roller harnessesresponsive to the operating conditions. A sensor device 26 is supportedto sense vibrations and orientation of the elevator car 12 relative to adesired orientation. The sensor device 26 is preferably an accelerometerfor sensing vibrations within the structure of the elevator car 12.Although an accelerometer is used in the illustrated example, anysensing device known in the art may be used for obtaining information oncurrent conditions such as vibrations or orientation of the elevator car12. Information from the sensor device 26 is provided to the controller24, which responsively controls the roller harnesses to adjust the ridequality. In the illustrated embodiment the controller 24 is supportedfor movement with the elevator car 12, however, the controller 24 maybedisposed in any other location.

Given this description, those skilled in the art will be able to programa commercially available controller or to develop dedicated hardware,software of both to achieve the desired roller hardness control to meettheir specific needs.

Each roller 16 is disposed adjacent a magnetic field generator 18. Themagnetic field generator 18 produces the magnetic field 20. Preferably,each of the plurality of rollers 16 is disposed adjacent a separatecorresponding magnetic field generator 18. Separate magnetic fieldgenerators 18 for each roller 16 provide independent control of rollerhardness for each roller 16.

Referring to FIG. 2, in one embodiment, each magnetic field generator 18comprises an electromagnet 21 configured to create an applied magneticfield 20 of varying strength in a generally known manner. Anelectromagnet includes a coil energized in proportion to a desiredstrength of the magnetic field 20. The electromagnet 21 varies fieldstrength in proportion to signals from the controller 24 to change thehardness of the corresponding roller 16.

Referring to FIG. 3, in another embodiment, the magnetic field generator18 comprises a permanent magnet 19. Moving the permanent magnet 19relative to a roller 16 (as indicated by arrows 38 for example)selectively varies the strength of the magnetic field 20 applied to theroller 16. Although an electromagnet and a permanent magnet are shown asexample field generators, it is within the contemplation of thisinvention to utilize any device configured to produce a varying magneticfield adjacent the rollers 16.

Referring to FIG. 4, in one example each roller guide assembly 14includes three rollers 16 guiding along three surfaces of the guide rail28. Each of the rollers 16 is supported for rotation about an axis 34.The roller guide assembly 14 guides the elevator car 12 within thehoistway to maintain proper orientation of the elevator car 12 and toprovide a smooth, quiet ride. Loads exerted on each of the rollers 16 ofany single roller assembly 14 vary with loads on and speeds of theelevator car 12. With this invention, the roller hardness can beoptimized to vary the dampening properties of each roller 16 toaccommodate and eliminate undesirable vibration, thus improving ridequality.

Referring to FIGS. 5 and 6, each roller 16 includes a membrane 30containing a fluid 22 having a viscosity that changes in response to thechanges in strength of an applied magnetic field 20 (FIG. 2 and 3). Thefluid 22 in one example comprises a known, magneto-rheological fluidcontaining suspended particles reactive to the magnetic field 20. Thesuspended particles within such a fluid form columnar structuresparallel to the applied magnetic field 20 in a known manner. Alignmentof the columnar structures restrict motion of the fluid 22 to increasefluid viscosity. The change in viscosity of the fluid 22 changes thedampening characteristics of the roller 16.

It is within the contemplation of this invention to utilize any type offluid responsive to an applied magnetic field to change viscousproperties. Those skilled in the art who have the benefit of thisdescription will be able to select magnet-rheological fluids andformulations according to application-specific parameters.

The membrane 30 is supported about a circumference of a solid disk 31and defines a generally annular cavity 36. The membrane 30 comprises thesurface of the roller 16 in guiding contact with the guide rail 28. Thefluid 22 within the membrane 30 changes viscous properties in responseto proportionate changes in strength of the applied magnetic field 20.Viscosity changes in the fluid 22 results in corresponding changes inhardness of the roller 16 to compensate and dampen vibrations of theelevator car 12.

Referring to FIG. 1, during operation of the elevator system 10, thesensor 26 communicates information indicative of vibration andorientation of the elevator car 12 to the controller 24. The controller24 compares the information on vibration and orientation from the sensor26 to desired conditions. The sensing device 26 senses currentconditions of the elevator car 12 that result from loads, guide railinconsistencies, vibrations, speed and many other operational parametersand mechanisms required for the operation of the elevator system 10

The controller 24 compares the sensed condition to a desired conditionand responsively controls each magnetic field generator 18 to produce acorresponding magnetic field 20 to control the viscous properties of thefluid 22 and obtain a desired hardness for each roller 16. The strengthof the magnetic field 20 is varied for each specific roller 16 inproportion to a difference between the desired condition and a sensedcondition. The changing hardness optimizes dampening properties for eachroller 16 to dampen and isolate vibrations of the elevator car 12.Further, the controller 24 independently controls the hardness of eachroller 16 such that the combined effect of dampening properties resultsin an optimized, smoother ride.

Operation of the elevator system 10 of this invention reduces theeffects of vibration during movement of the elevator car 12 to improveride quality and reliability. Further, optimization of the selectivelyvariable dampening characteristics of the inventive rollers 16accommodates a wider variety of guide rails 28.

The foregoing description is exemplary and not just a materialspecification. The invention has been described in an illustrativemanner, and should be understood that the terminology used is intendedto be in the nature of words of description rather than of limitation.Many modifications and variations of the present invention are possiblein light of the above teachings. The preferred embodiments of thisinvention have been disclosed, however, one of ordinary skill in the artwould recognize that certain modifications are within the scope of thisinvention. It is understood that within the scope of the appendedclaims, the invention may be practiced otherwise than as specificallydescribed. For that reason the following claims should be studied todetermine the true scope and content of this invention.

1. A roller guide assembly (14) for an elevator system (10) comprising:a roller (16) having a hardness that varies responsive to a magneticfield (20), wherein the roller (16) includes a membrane (30) containinga fluid (22) having a viscosity that changes responsive to said magneticfield (20).
 2. The assembly of claim 1, wherein said fluid (22)comprises a magnet-rheological fluid.
 3. The assembly of claim 1,wherein the membrane (30) defines a generally annular chamber (36)supported about a disk (31).
 4. The assembly of claim 1, including amagnetic field generator (18) adjacent said roller (16), said magneticfield generator (18) selectively controllable to vary the hardness ofsaid roller (16).
 5. The assembly of claim 4, including a plurality ofsaid rollers (16) and a corresponding plurality of separately actuatablemagnetic field generators (18).
 6. The assembly of claim 4, wherein saidmagnetic field generator (18) comprises an electromagnet (21).
 7. Theassembly of claim 4, wherein said magnetic field generator (18)comprises a permanent magnet (19).
 8. An elevator system (10)comprising: at least one guide rail (28); an elevator car (12) movablealong the guide rail (28); a roller (16) supported for movement withsaid elevator car (12), said roller (16) rolling along a surface of saidguide rail (28) and having a hardness that varies responsive to amagnetic field (20); and a magnetic field generator (18) thatselectively generates said magnetic field (20), wherein said roller (16)includes a membrane (30) containing a fluid (22), said fluid (22) havinga viscosity that changes responsive to said magnetic field (20).
 9. Thesystem of claim 8, wherein said membrane (30) defines a generallyannular chamber (36) supported about a disk (31).
 10. The system ofclaim 8, wherein said membrane (30) is in rolling contact with saidsurface of said guide rail (28).
 11. The system of claim 8, including aplurality of rollers (16) and a corresponding plurality of magneticfield generators (18).
 12. The system of claim 11, including acontroller (24) that selectively and individually controls the magneticfield generators (18).
 13. The system of claim 8, including a sensordevice (26) that provides information regarding the orientation of saidelevator car (12) and a controller (24) that receives information fromsaid sensor device (26) and responsively controls said magnetic field(20) generator to vary said roller hardness.
 14. A method of controllingvibration of an elevator car (12) that has an associated plurality ofrollers (16) adapted to guide the elevator car (12) along a guide rail(28) comprising the steps of: a) determining a condition of the elevatorcar (12) relative to a desired condition; b) selectively varying ahardness of at least one of the rollers (16) responsive to saiddetermined condition by varying a magnetic field associated with the atleast one of the rollers (16); and c) providing the at least one of therollers (16) with a membrane (30) containing a fluid having a viscositythat changes responsive to the magnetic field.
 15. The method of claim14, including varying the strength of the magnetic field (20)independently for each of the rollers (16).
 16. The method of claim 14,wherein step (a) includes determining a level of vibration of the car asthe car moves along the guide rail.